1. Field of the Invention
The present invention relates a wheel fan of a range hood used in the kitchen and particularly to a wheel fan of a ventilator having improved blades and mechanisms for locating a top plate.
2. Description of the Prior Art
The wheel fan of a conventional range hood, as shown in FIG. 1, has a top cover 100A concave at its center like a bowl; rectangular blades 200A ranging radially and held by the top cover 100A; a plane circular bottom plate 300A to the bottom of the blades 200A; and centrifugal blades 400A held by a central hole on the bottom plate 300A. It performs badly and makes much noise.
The wheel fan of a conventional range hood developed later, as shown in FIG. 2, has a top plate 100B sinking inwardly, a bent bottom ring 300A, and blades 200B held by the top plate 100B and bottom plate 300B. Because the blades 200B are independent, they are connected to the bottom ring 300B and then the top plate 100B one by one, so that assembly is laborious. Furthermore, the performance is unstable due to a change of the distance between any two adjacent blades.